Evidence suggestive of harmful effects of occupational exposure on the reproductive system and related outcomes has gradually accumulated in recent decades, and is further compounded by persistent environmental endocrine disruptive chemicals. These chemicals have been found to interfere with the function of the endocrine system, which is responsible for growth, sexual development and many other essential physiological functions. A number of occupations are being reported to be associated with reproductive dysfunction in males as well as in females. Generally, occupations involving the manufacture/or application of some of the persistent chemicals that are not easily degradable as well as bio-accumulative chemicals, occupations involving intensive exposure to heat and radiation, occupations involving the use of toxic solvents as well as toxic fumes are reported to be associated with reproductive dysfunction. Occupational exposure of males to various persistent chemicals have been reported to have male mediated adverse reproductive outcomes in the form of abortion, reduction in fertility etc. with inconclusive or limited evidence. Nevertheless, there is a need for more well designed studies in order to implicate any individual chemical having such effects as in most occupations workers are exposed to raw, intermediate and finished products and there are also several confounding factors associated with lifestyles responsible for reproductive dysfunction. There is an urgent need to look at indiscriminate use of persistent chemicals especially pesticides and persistent organic pollutants (POP's) as these chemicals enter the food chain also and could be potential for exposure during the critical period of development. It is also necessary to impart information, and to educate about the safe use of these chemicals, as a very sensitive reproduction issue is involved with exposure to these chemicals. Occupational exposures often are higher than environmental exposures, so that epidemiological studies should be conducted on these chemicals, on a priority basis, which are reported to have adverse effects on reproduction in the experimental system.
The profiling of gene expression patterns with DNA microarrays is recently being widely used not only in basic molecular biological studies but also in the practical fields. In clinical application, for example, this technique is expected to be quite useful in making a correct diagnosis. In the pharmacological area, the microarray analysis can be applied to drug discovery and individualized drug treatment. Although not so popular as these examples, DNA microarrays could also be a powerful tool in studies relevant to occupational health. This review will describe the outline of gene expression profiling with DNA microarrays and prospects in occupational health research.
Musculoskeletal disorder (MSD) is a common problem among workers. In spite of the numerous reports on MSD in various specific groups of workers, few data on the prevalence in the general working population are available except for back pain. We analyzed the information collected through a nationwide survey in Taiwan in 1994 to estimate the prevalence of MSD by age, gender, and education level and identify high-risk industries. In the survey, a standard questionnaire was distributed to a representative sample of 22,475 non-self-employed workers in Taiwan. National estimates were obtained by applying a weight to each participant. Among the sampled workers, 18,942 (84.3%) participated, and 37.0% (standard error=0.4%) had MSD. Female workers had a significantly higher overall prevalence than male workers (39.5% vs. 35.2%, p<0.05). Education and age also had significant associations with MSD (p<0.001 in both genders). “Lower back and waist” were the most frequently affected body parts (18.3% among males and 19.7% among females), but the prevalence of MSDs of the neck, shoulders, hands and wrists were also above 10%. The top ten high-risk major industries for MSD of various body parts for each gender were identified, and some industries, including “Basic Metal Industries” and “Buildings Construction,” were among the top ten for multiple body parts. Our study showed that MSDs of body parts other than the back are also prevalent, especially in the neck, shoulders, hands and wrists. We also identified high-risk industries for further research and intervention.
It is reported that dentists are exposed to heavy metals in their clinics. To assess the risk of developing lung cancer among male Japanese dentists, we conducted a retrospective cohort study of 3,314 members of Osaka Dental Association (Osakafu-Shikaishikai). During 1964-1997, 39 were diagnosed with lung cancer, which figure was obtained from the file of the Osaka Cancer Registry. The observed number of lung cancers was compared with the expected number calculated by multiplying the number of person-years at risk by the corresponding age- and calendar time-specific incidence rate from the Osaka Cancer Registry data. The male dentists had no significantly different risk than general population.(O/E=1.01, 95%CI=0.72-1.39). Contrary to expectation, these findings indicate that Japanese dentists had almost the same overall risk of developing lung cancer as the general population.
Psychosocial risk factors have been considered as characteristics of the work environment rather than an individual issue, but their presence in the workplace is usually measured by self-reported questionnaires, based on worker attitudes. The objective of the study was to compare a self-reported measure of psychological job demands in a bus driver sample with selected indicators of bus company activity, as external ‘objective’ indicators, in order to assess its external validity. The final sample included 713 drivers in 41 routes. Self-reported measures of psychosocial work risk factors were obtained by the Job Content Questionnaire (JCQ). Four external indicators were available for each route: passengers, break times, bus incidents, and regulating actions. Spearman's correlation coefficient was estimated to assess the validity. Correlation coefficients showed that self-reported psychological demands were statistically significant correlated (p<0.05) with two external indicators: bus incidents (rho=0.397), and regulating actions (rho=0.475). Self-reported psychosocial risk factors have been compared with independent external indicators of the psychosocial work environment, trying to avoid any subject's perception. According to our results, psychological demands measured by the JCQ seem to reflect the actual psychosocial work environment. Other studies are necessary to confirm these results and to assess job control and job social support. This would be another step in improving our knowledge of the quality of measurement of psychosocial risk factors.
Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are synthetic surfactants used in Japan. An epidemiological study of workers exposed to PFOA revealed a significant increase in prostate cancer mortality. A cross-sectional study of PFOA-exposed workers showed that PFOA perturbs sex hormone homeostasis. We analyzed their concentrations in surface water samples collected from all over Japan by LC/MS with a solid phase extraction method. The lowest limits of detection (LOD) (ng/L) were 0.06 for PFOA and 0.04 for PFOS. The lowest limits of quantification (LOQ) (ng/L) were 0.1 for both analytes. The levels [geometric mean (GM); geometric standard deviation (GS)] (ng/L) of PFOA and PFOS in the surface waters were GM (GS): 0.97 (3.06) and 1.19 (2.44) for Hokkaido-Tohoku (n=16); 2.84(3.56) and 3.69 (3.93) for Kanto (n=14); 2.50 (2.23) and 1.07 (2.36) for Chubu (n=17); 21.5 (2.28) and 5.73 (3.61) for Kinki (n=8); 1.51 (2.28) and 1.00 (3.42) for Chugoku (n=9); 1.93 (2.40) and 0.89 (3.09) for Kyushu-Shikoku (n=15). The GM of PFOA in Kinki was significantly higher than in other areas (ANOVA p<0.01). Systematic searches of Yodo and Kanzaki Rivers revealed two highly contaminated sites, a public-water-disposal site for PFOA and an airport for PFOS. The former was estimated to release 18 kg of PFOA/d. PFOA in drinking water in Osaka city [40 (1.07) ng/L] was significantly higher than in other areas. The present study confirms that recognizable amounts of PFOA are released in the Osaka area and that people are exposed to PFOA through drinking water ingestion.
The present study was conducted to clarify the direct effects of active listening (AL) training given to middle managers in a local government. Altogether, 345 middle managers participated in 13 AL training sessions over two years. We developed the Inventive Experiential Learning (IEL) method, and used it as the central training method in this study. To investigate how well the participants learned AL, we asked the middle managers to answer a shorter version of the Active Listening Attitude Scale (ALAS) consisting of two subscales-i.e. “Listening Attitude” and “Listening Skill”-before training, one month after and three months after training. Altogether, 284 middle managers answered the questionnaire three times. The scores of each subscale were analyzed by repeated measurement analysis of variance. The participants were divided into three groups using the percentile values of the original sample of ALAS, i.e. low-score group (-24%), medium-score group (25-75%) and high-score group (76%-), and the proportionate changes were examined. The results showed both the “Listening Attitude” and “Listening Skill” subscales increased significantly after training. Analysis of the percentiles showed that the proportion of the low-score group decreased and that of the high-score group increased in both subscales, from one to three months after training. These changes are considered to indicate that the participants have learned AL although they attended AL training for only one day.
Although it has been found that legionellae can exist in a 24-h hot water bath (24HHWB), which has been used recently in Japan, whether longer use of the 24HHWB causes legionellosis is unclear. The present longitudinal study was conducted in 2000 to investigate the 3-yr change in antibody titers in association with the continuous use, non-use, or canceling the use of the 24HHWB, and possible factors relating to the antibody changes. Ninety-two subjects (85 males and 7 females), who had had their anti-Legionella pneumophila (Lp) serum antibody titers measured in our initial study in 1997 and consented to blood sampling 3 yr later, were selected as subjects. There were no clinical cases who had experienced Legionnaires' disease or Pontiac fever during the 3 yr. The continuous users showed no significant changes in antibody titers within 3 yr, whereas the continuous non-users had a significant increase in antibody titers against the Lp serogroup (SG) 5 and 6. Eleven ex-users of the 24HHWB showed a significant decrease in antibody titers against Lp SG 6. The changes in the 24HHWB use, job sector, stress coping strategies, and alcohol-drinking habit were associated with the changes in antibody titers against Lp SG 1, 5 or 6. The anti-Lp antibodies were considered to be IgM dominant. In conclusion, this study indicates that 24HHWB use by healthy subjects does not tend to result in a higher onset risk of legionellosis, even if it is continuously used for 3 yr, although 24HHWB use is likely to induce production of antibodies against legionellae.